Bladed member and method for making



L. J. STOFFER BLADED MEMBER AND METHOD FOR MAKING 2 Sheets-Sheet 1 Oct.1, 1968 Original Filed Feb. 25, 1966 t-El 1 AZ 5 /J c f 5 5 m: i d I a(1D I l "I, 36 ,4564 F drier INVENTOR.

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BLADED MEMBER AND METHOD FOR MAKING Original Filed Feb. 25, 1966 2Sheets-Sheet 2 III'MAJE/ United States Patent 3,403,844 BLADED MEMBERAND METHOD FOR MAKING Lewis J. Stoifer, Cincinnati, Ohio, assignor toGeneral Electric Company, a corporation of New York Continuation ofapplication Ser. No. 541,410, Feb. 25, 1966. This application Oct. 2,1%7, Ser. No. 672,106 15 Claims. (Cl. 230134) ABSTRACT OF THE DISCLOSUREThe disclosure illustrates a method of making a compositely formed,bladed rotor of the type which can be used in the compressor of a gasturbine engine. The rotor is fabricated by drawing a continuous strandof fibrous material, e.g., glass fibers, along blade-defining portionsof a form. The strand is drawn under tension in accordance with apredetermined winding pattern of reaches so that the blade-definingportions of the form are filled to approximately the same extent.Provision is also made for winding a circular band which encompasses theouter ends of the blade to give additional strength. The wound strandsmay be covered with glass cloth to protect the fiber thereof. Theoompositely formed rotor is bonded together, as by an appropriate resin,while on the form. An alternate embodiment illustrates the use of awinding form having blade-defining portions on opposite sides whichenable the simultaneous winding of two rotors.

This application is a continuation of application Ser. No. 541,410,filed Feb. 25, 1966, now abandoned.

The present invention relates to circular bladed members such as bladedwheels and bladed fluid guide members. More particularly it relates tocircular rotor or stator members having integral blades radiating from asupport portion and to a method of making such members.

In many devices wherein fluid-moving or fluid-guiding articles such asrotors, stators or fluid guide members are to be used, for example, ingas turbine apparatus, it is desirable that components such as bladesand shrouds normally included in such an article be constructed as anintegral part of the article. A purpose for such a construction is toreduce assembly costs and mechanical failure under conditions of heavyloading. Attempts have been made to provide fluid-moving rotors bymachining the article from a single metallic piece or casting metalalloys into complex molds. However, the raw material costs and the timerequired for such machining as well 0 as problems involved in making andusing the complicated casting molds required, have increased the cost ofsuch articles so as to militate against their use. Additionally, metalrotors made by either of the above-mentioned casting or machiningmethods are too heavy for use in applications requiring a high ratio offluid-moving capacity to rotor weight.

To satisfy the requirement of a high capacity-to-weight ratio,lightweight plastic rotors have been considered for use. Whereunreinforced plastics are used, the rotor can be used only in certainrelatively low loading applications due to the poor structural integrityof the plastic material. To improve this structural integrity, bundlesof reinforcing fibers have been used to form a core about which theplastic blades are molded. However, these bundles are seldom stressedequally, after assembly in a rotor, as they should be for optimum rotorperformance. In the absence of equal stressing around the entire rotor,the blades tend to distort unevenly under heavy centrifugal loadingthereby detrimentally altering the performance characteristics of therotor.

In some cases, an outer circular shroud is required 3,403,844 PatentedOct. 1, 1968 around the blades. Where the circular shroud is attached tothe tips of the bundle-reinforced blades, the uneven distorting effectsof heavy centrifugal loading are intensified. The use of such shrouds inprior art plastic rotors has caused an additional problem in that theshroud is not formed integrally with the blade-reinforcing bundles sothat material failure may occur at the shrouds junc tures with the bladetips.

It is accordingly one object of the present invention to provide animproved method of making a complete or integral bladed circular articleor article core wherein length portions or reaches of reinforcingmaterials are equally stressed during the formation of the article orcore so as to minimize the uneven distorting effects of centrifugalloading.

It is another object of the present invention to provide an improvedmethod of making an integral rotor or fluid guide member having acircular shroud formed integrally with reaches of blade-reinforcingmaterials.

Still another object is to provide an improved bladed member having areinforcing core in which reaches of reinforcing material are equallystressed.

It is a further object of the present invention to provide an improvedrotor having a reinforcing core in which reaches of reinforcingmaterials are equally stressed and in which a circular shroud is formedintegrally with the reaches of blade-reinforcing materials.

To fulfill these objects, the present invention provides a method ofmaking an integral bladed circular member, such as a rotor diskcomprising a circular support and blades radiating from the support. Themethod includes winding a continuous strand, such as a roving, filamentor tape, on a suitable circular form while applying two forces to thestrand. The first force is a uniform tension force applied along theaxial direction of the strand; the second force is applied at an angleto the axis of the strand and toward the form. The continuous strand iswound on the form in a series of reaches, each consecutive reach beingat an angle diiferent from that of the next preceding reach. The memberis built in multiple layers disposed substantially normal to the centralaxis of the member. After winding, the strand is bound together on theform, such as by a suitable curable binder preferably carried by thestrand, to produce the integral bladed member.

The integral bladed member of the present invention comprises a centralsupport and blades radiating from the support, the support and bladesbeing made from a strand which is integral both with a blade and itsadjacent portion of the support. The strand in the blade is underuniform radial tension with respect to the circular member whereas thestrand in the support adjacent the blade is under uniform tensiongenerally in the tangential direction with respect to the circular shapeof the member.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which constitutes the presentinvention, the invention may best be understood by reference to thefollowing description when taken in conjunction with the accompanyingdrawings in which:

FIGURE 1 is an isometric view of a form or jig suitable for use with themethod of the present invention, upon which form several reaches ofstrand material in a partially wound rotor core are shown;

FIGURE 2 is a partially sectional isometric view showing pressureelements suitable for use with the method of the present inventionassembled with the form and in position in a heated platen press whichmay be used to bind the strand into a rotor core;

FIGURE 3 is a fragmentary plan view of an integral bladed rotor corehaving a central support as well as innet and outer shrouds integralwith the blades, the central support partially impregnated with foamablematerial;

FIGURE 4 is a fragmentary sectional view of a blade of FIGURE 3 and itsassociated shrouds and support portions; and

FIGURE 5 is an isometric view of a form upon which two juxtaposed rotorsmay be generated when carrying out the method of the present invention.

Referring now to the drawings, FIGURE 1 shows a circular winding form orjig suitable for use with the method of the present invention to producethe shrouded and bladed rotor disk core of FIGURE 3. Reference to bladeddisk in this specification is intended to mean a bladed solid circularmember as well as a bladed annulus. The jig 10 includes a ring ofinwardly-pointing, bulletshaped platform patterns, each of which isidentical to platform pattern 11. Spaced from and encircling patterns 11are a like number of sectors, each of which is identical to sector 12.

The radial edges of adjoining sectors are slightly separated one fromthe other as are the adjoining edges of the platform patterns and theiradjacent sectors. The spaces between the sectors 12 in which the bladecore portions 24 of FIGURE 3 are formed are shown for simplicity ofpresentation to define planes in each of which the axis of the rotorlies. However, it should be understood that such sectors can be shapedand contoured so as to define contoured and angled spaces therebetweenwhich would conform with the angled and twisted airfoil shape of gasturbine blading when mounted in a rotor.

The platform patterns and sectors are secured, such as by bolting (notshown), to a subjacent cylindrical disk 13, the outside diameter ofwhich is slightly larger than the diameter of the circle defined by theouter circumference of the ring of sectors 12. An annular metal bearing14 may be releasably secured to the disk 13 at the center of the centralarea 15 enclosed within the ring of platform patterns 11.

The first step of the manufacturing process which results in an integralbladed and shrouded rotor core of FIGURE 3 involves the generation ofthe rotor core on the above-described form or jig. The core is generatedby systematically and repeatedly winding on the form a continuous strandor roving 36 to which has been applied a uniform first force along theaxis of the strand to place the strand under uniform axial tension. Asecond force is applied to the strand concurrently with the first forceand toward the form.

The continuous strand is wound in a series of reaches, described in moredetail later, through the spaces or gaps such as A in the radialdirection, H in the circular direction or around the outer periphery ofa sector such as 12 in FIGURE 1. Thus each of the reaches, which aresegments of the continuous strand, are wound in a series according tothe sequence selected, each consecutive reach being at an angle or Woundin a direction different from the angle or direction of wind of the nextpreceding reach.

A series of reaches are wound until a substantially uniform layer ofstrand is disposed through the gaps and through the central area 15.Then a second series of reaches is wound on the form thus to build thearticle in multiple layers disposed substantially normal to the axis ofthe article. At this point the gaps between elements have been filledwith the continuous strand or roving and that portion of the centralarea 15 not Occupied by hub or plug 14 has been crisscrossed by multiplelayers of the roving.

For highly stressed performance requirements, cloth such as binderimpregnated woven glass cloth can be interspersed between layers of therovings. The cloth adds to the structural integrity of the disk portionparticularly in the axial direction. In addition, it prevents excessflow of binder during curing.

One type of high strength roving which is well suited for use underhighly stressed conditions is sometimes referred to commercially as endroving. It includes over 2000 separate glass filaments which aregathered parallel and twisted into a single continuous strand. Thestrand is then impregnated with a curable resinous material such asthermo'setting epoxies, phenolics and the like prior to the windingprocess. However, it is obvious that other materials or rovingconstructions might be used. For instance, boron coated tungstenfilaments might be used in place of glass; a single filament of aplastic or metallic material might be suitable in certain applications.The binder can, in appropriate cases, be metallic such as a brazingalloy.

The roving 36 can be wound in any one of a number of sequences includingmany series of windings with the particular sequence used depending onthe desired application.

Referring to FIGURE 1, an example of one winding series of a sequencecan start with a roving or strand 36 through blade core gap A towardblade core gap B adjacent sector 12, around the outer periphery ofsector 12 and through the blade core gap C adjacent sector 12. Then theroving is passed across central area 15 and through blade core gap Dadjacent sector 12a, around the outer periphery of sector 12a andthrough blade core gap E. The roving is then again passed across centralarea 15 toward blade core gap F, and so on around the jig symmetricallyand back through blade core gap A. At the beginning of the second and ofeach consecutive subsequent blade core winding series the roving 36::might be directed from blade core gap A to blade core gap C and insuccessive series to blade core gap G at the beginning of the series.Thus the winding is shifted around the jig on each turn for symmetry andimproved structural integrity.

In order to produce the integral inner shroud or blade platform portion26 in FIGURE 3, a second set of winding series can be alternated withthe above described series. The second series could follow the same planas the first series except that the roving would 'be directed throughthe space between the sector and the platform pattern such as space Hbetween sector 12 and platform pattern 11. To generate a continuousouter shroud with high hoop strength integrity, additional roving can bewound on the completed core structure a multiplicity of times around theouter periphery.

The strand material filling the blade gaps such as A, B, C, etc., definecores for the finished blades. Similarly, the strand or roving 36 whichis wound around the outer periphery of the jig 10 when the roving ispassed around a sector from one blade gap to an adjacent one defines thecore for an outer circular shroud 25. When passed through a gap such asH between a sector and a platform pattern it defines the core for aninner shroud or blade platform 26. Since outer -shroud and inner shroud26 of FIGURE 3 are formed integrally with the blades, there is littlepossibility of material failure at the junctures between the blades andthe shrouds.

Just as the winding sequence may be changed for different articleshapes, so may the tension force with which the roving 36 is to be woundbe changed. However, the tension is not varied once the winding of anyparticular article or article core has begun. For example, a 15 pounduniform tension is suitable for a 20 end roving. As a result of thisuniform tension on the roving, each of the reaches making up the core isstressed to the same extent as the others. Naturally, the blades, whichare in tension in the radial direction with respect to the circulararticle, will also be equally stressed one to the other as their cores.are formed from multiple layers of equally-stressed reaches. Thus theblades will not tend to distort or flex unevenly under heavy centrifugalloading such as is experienced by an axial flow compressor rotor in agas turbine application.

Aftcr the wound core has been generated, the strands must be boundtogether or made rigid. One method of binding the strands of the coreinvolves the use of pressure elements shown in position over form or jig10 in FIGURE 2. These pressure elements include an outer metal band 16which encircles the roving at the outer periphery of the sectors of jig10. An intermediate metal band 17 lies between outer band 16 and theouter periphery of the sectors and is seated on the edge of the rovingencircling the outer periphery of the sectors. There is an inner metalvand 18 which may be seated on the roving in the circular gap betweenthe platforms 11 and the adjacent sectors 12 of FIGURE 1. A plurality ofmetal strips, such as strip 19, are seated on the edges of the roving inthe radial blade core gaps between adjacent sectors. In addition to thevarious bands or strips, there is included a disk 20, which can have acentrally-located aperture in registry with the annular bearing 14 ofFIG- URE 1 if such a central plug is used, and a scalloped periphery 37in registry with the pointed inner ends of the billet-shaped platformpatterns.

As may be seen in FIGURE 2 these pressure elements are positioned on thejig 10, which is placed on the lower plate 21 beneath upper plate 23 ofa heated platen press shown generally at 22. Plates 21 and 23 aremovable one toward the other such as by lifting plate 21 toward parallelupper plate 23 by a suitable hydraulic mechanism disposed beneath thelower plate. The pressure elements, heated as a result of their being incontact with the heated press surfaces, not only compress the layers offibers as the plates are brought one toward the other, but also cure thecurable binder material with which the strands such as rovings have beenimpregnated.

After a predetermined period of time has elapsed, the upper and lowerplates are moved apart so that the jig and pressure plates can beremoved and the article such as a rotor core taken therefrom. As may beseen in FIG- URE 3, the core resulting from use of the jig and pressureelements of FIGURES 1 and 2 includes a plurality of blade core portions24, an outer circular shroud 25, a concentric inner shroud or platform26, and an apertured central support or hub area 27 formed by thecrisscrossed reaches of roving. In certain stator or fluid guideassemblies, either inner shroud 26 or outer shroud 25 could constitutethe support. The area enclosed within the inner shroud 26 can be filledwith a foamable material such as a foamable epoxy resin shown at 2-8,which, when foamed and cured, serves both to prevent extraneous gas flowthrough the hub area of the fan and to prevent vibration of the reachescrossing through the hub area. In certain situations, the circular outershroud 25 may be unnecessary. If so, the shroud may be removed merely bytrimming it from the ends of the blades.

To enhance the axial integrity of the article such as the rotor core ofFIGURE 3, the rotor core and particularly the blade portions and theouter shroud, if it remains, may be surfaced or overwrapped withsuitable strips or sheets of material bonded to the core as shown at 29in FIGURE 4. A preferred material for this purpose is thermosettingplastic impregnated woven glass cloth which can be cured with the coreduring the regular press curing process.

A preferred method of applying a surface or facing of sheet material isto line the various gaps and surfaces of the jig with the sheet materialbefore generating the core. After final winding, all other exposedsurfaces such as of area in FIGURE 1 and the outer periphery of theouter shroud can be covered with the sheet. FIGURE 4 is a fragmentarysectional view of a glass cloth covered rotor in which airfoil shapedblade core portion 24, outer shroud 25, inner shroud 26, central supportmember 27 (FIGURE 3) and foamed material fill 28 have integrally bondedthereto a cloth material 29.

Although the platform patterns have been removed from the hub area inthe rotor and can be filled with a lightweight material such as 28 shownin FIGURE 3, it may be desirable to make hollow platform patterns of alightweight material and leave them in place forming the blade portionsand hub area about them for weight reduction purposes. If the platformpatterns are to be used in this manner, they can best be provided withcorrugated or grooved sides so that each pattern will be effectivelyinterlocked with the adjacent reaches in the finished rotor.

Referring now to FIGURE 5, there will be seen a jig 30 upon which a pairof rotor cores may be generated simultaneously. The jig includes anupper winding form 31 which is back to back with a lower winding form32. Each of these forms includes a plurality of slanted airfoil shapedwinding surfaces such as surfaces 33 and 33a on form 31 and 33' and 33aon form 32 respectively separated by vertical spacers such as spacers 34and 34.

A rotor core is generated on this jig 30 by repeated winding acontinuous impregnated stand such as in the form of a strip of tapealong the winding surfaces and across the hub area in the same generalmanner as was described earlier. However, in this example, the tape isnot wound circumferentially around the outer periphery of the jig as wasdone before. Instead, it is Wound from a winding surface on one of thewinding forms to an adjacent winding surface on the opposite windingform. An example of this winding technique may be seen at 38, 38a and38b representing several reaches in a series wound around the jig 30.Once the back to back cores have been generated, the impregnated tape isplaced under pressure with a mating die or form and cured to bind orrigidify the wound strand into a rotor structure. The tape strandsbetween the upper and lower winding forms, such as along circumferentialdotted line 39, are ground or cut away to separate the two rotors. Thehub areas of each of these rotors may be impregnated with a foamingmaterial in a manner similar to that set forth above in the precedingdescription of the method of this invention. Similarly, a cloth coveringcan be applied as described before.

As will be evident from the aforegoing description, certain aspects ofthe invention are not limited to the particular details set forth inthis specification. It is contemplated that various modifications willoccur to those skilled in the art and it is therefore intended that theappended claims shall cover such modifications as do not depart from thetrue spirit and scope of the invention.

What is claimed is:

1. In a method of making an integral bladed circular member including asupport and a plurality of blades integral with and radiating from thesupport, the steps of:

winding a continuous strand on a suitable form while applying a uniformtension force to the strand along its axial length and at the same timeapplying a second force to the strand at an angle to the axial length ofthe strand and toward the form,

the continuous strand being Wound on the form in a series of reaches,each consecutive reach being at an angle different from that of the nextpreceding reach, the member being made in a plurality of layers disposedsubstantially normal to the central axis of the member, and then bindingthe wound strand together while on the form to produce the integralbladed member. 2. In the method of claim 1 in which: sheet material islocated on a surface of the wound member prior to binding the woundstrand together, and then the sheet material is bound to the strandconcurrently with binding together the wound strand on the form.

3. In the method of claim 1 in which the strand is impregnated with acurable binder prior to winding on the form.

4. In the method of claim 1 for making an integral bladed disk memberincluding a central support, a plurality of blades integral with andradiating from the support and an outer circular shroud integral withthe blades at their radially outward end, the steps of:

winding a continuous strand impregnated with a curable binder on asuitable form while applying a uniform tension force to the strand alongits axial length and at the same time applying a second force to thestrand at an angle to the axial length of the strand and toward theform,

the continuous strand being wound on the form in a series of reaches,each consecutive reach being at an angle different from that of the nextpreceding reach, the member being made in a plurality of layers disposedsubstantially normal to the central axis of the member, and thenrigidifying the member by binding the wound strand together while on theform to produce the integral bladed member.

5. In the method of claim 4 in which sheet material impregnated with acurable binder is placed between layers of the central support.

6. In the method of claim 4 in which:

sheet material impregnated with a curable binder is located on a surfaceof the wound member prior to binding the wound strand together, and thenthe sheet material is bound to the strand concurrently with bindingtogether the wound strand on the form.

7. A method as in claim 1 of making an integral bladed disk memberincluding a central support, a plurality of blades integral with andradiating from the support and an outer circular shroud integral withthe blades at their radially outward end, comprising the steps of:

winding 2. continuous curable plastic binder impregnated strand on asuitable form while applying a uniform tension force to the strand alongits axial length and at the same time applying a second force to thestrand at an angle to the axial length of the strand and toward theform,

the continuous strand being wound on the form in a series of reaches,each consecutive reach being at an angle different from that of the nextpreceding reach and alternating between circular and chordwisedirections with respect to the surface of the disk member normal to itscentral axis until the portion of the member within the form has beenmade,

winding additional strand circumferentially around the strand at theouter periphery of the form to increase the thickness of the windings ofstrand defining the outer circular shroud,

the member being made in a plurality of layers disposed substantiallynormal to th central axis of the member,

applying heat and pressure to the wound strand while on the form topress adjacent reaches of strand one toward the other and to cure thebinder impregnating the strand to bind the strand together into anintegral bladed circular member, and then removing the member from theform. 8. The method of claim 7 in which: sheet material is placedbetween layers of the central support and is located on a surface of thewound member prior to applying heat and pressure, and then applying heatand pressure to the sheet material and to the wound strand concurrentlywhile on the form to cure the binder impregnating the strand and sheetwhile pressing adjacent reaches of strand one toward the other andpressing the sheet material toward the strand to bind the strand andsheet together into an integral circular member.

9. An integral bladed member comprising:

a support, and

a plurality of blades radiating from and integral with the support,

the support and blades being made from a strand which is integral bothwith a blade and its adjacent portion of the support,

the strand in the blades being under uniform tension radially withrespect to the member, whereas the strand at the surface of the supportbetween the blades is under uniform tension generally circumferentiallywith respect to the shape of the member.

10. An integral bladed disk member comprising:

a circular central support,

a circular outer shroud, and

a plurality of blades radiating between and integral with both thesupport and the outer shroud,

the support, the blades and the outer shroud being made from acontinuous, wound strand defining a plurality of layers disposedsubstantially normal to the central axis of the member,

the strand in the blades being under uniform tension radially and thestrand in the surface of the support between the blades and in the outershroud being under uniform tension generally circumferentially withrespect to the circular shape of the disk member.

11. An integral bladed rotor comprising:

a central support,

a circular inner shroud surrounding and integral with the support,

a circular outer shroud, and

a plurality of blades radiating between and integral with both the innershroud and outer shroud,

the support, the inner shroud, the blades and the outer shroud beingmade from a continuous, wound strand defining a plurality of layersdisposed substantially normal to the central axis of the member,

the strand in the blades being under uniform tension radially and thestrand in the inner and outer shrouds between the blades being underuniform tension generally circumferentially with respect to the shape ofthe rotor.

12. The bladed rotor of claim 11 in which:

sheet material is disposed between layers in central support.

13. The bladed rotor of claim 11 in which:

sheet material is bonded to surfaces of the disk member.

14. In a method of making a compositely formed, generally circularmember having a plurality of radially extending blades, the steps of:

Can

winding a continuous strand on a form having means for definingangularly spaced, bladed portions extending radially of the axis of thecircular member to be made,

said strand being wound on said form by being repeatedly drawn, undertension, radially inwardly and outwardly along the blade-definingportions thereof, said strand being drawn radially along each of saidbladedefining portions approximately the same number of times so thateach blade comprises approximately equal portions of drawn strand, and

bonding the so drawn portions of strand together as components of acomposite bladed member.

15. In a method of making a compositely formed, generally circularmember as in claim 14 wherein:

said strand, each time it is drawn radially inwardly, is bent aroundsuitable means on the form and then drawn radially outwardly alonganother blade-defining portion, angularly spaced from said firstbladedefining portion.

References Cited UNITED STATES PATENTS 1,537,790 5/1925 Alpe 64l31,605,356 11/1926 Leipert 64-l3 2,857,094 10/1958 Erwin 230-1343,047,191 7/1962 Young 156l75 3,057,767 10/1962 Kaplan 156-172 HENRY F.RADUAZO, Primary Era/Miner.

